Abstract: Tests on micro-performances of hydration products, porjous structures, etc., mixed singly with slag-powder or fly-ash, and mixed with both slag -powder and fly-ash, were performed by using X-diffraction anlysis, differential scanning calorimeter, measuring-hole pressing with mercury procedure, scanning electron microscope etc. The test results showed that: the total hole area, average hole -diameter and sum porosity of the hydration products mixed with both slag-powder and fly-ash all get improvement as compared with that mixed singly with slag-powder or fly-ash; early, the reaction of the product mixed with slag-powder is faster than that mixed with fly-ash; late, the volcanic ash effect of fly-ash has been released and a large amount of hydration products generate on the surface o f fly-ash particals.